腐食環境下で機能維持可能なメタボリズムRC柱構造の開発

Abstract

現行の維持管理方策では，腐食が重度な場合，鉄筋の取替を含む大規模更新を行う．一方で，柱では支保工の設置等が必要となり容易には実施できない．そこで本研究では，軸力支持下での腐食鉄筋取替を容易にすることで，腐食環境下で構造物の機能維持を可能とするRC柱の開発を目指す．提案構造は，腐食を許容し腐食ひび割れ顕在時に取替が可能な可換部と，可換部取替時に軸力を支持する永続部からなり，供用しながら腐食鉄筋の取替が可能である．軸力支持下での取替実験及び正負交番載荷実験の結果，腐食の有無に依らず軸力支持下で鉄筋取替ができ，取替が復元力特性に影響を与えないことを確認した．また，取替時の永続部可換部間の付着の有無による影響を検証し，せん断ひび割れ抑制の観点から永続部可換部間の付着確保が望ましいことが分かった．

In current treatment of management system, the structural replacement including replacement of rebars is conducted when the corrosion is severe. However, it is not easy for column structure to replace corroded rebars because it requires the installation of timberings. In this paper, we aim to develop the metabolism RC column structure that can maintain the structural function under the corrosive condition by facilitating the replacement of rebars under axial force support. The proposal structure is made of two parts, exchangeable part and lasting part. The exchangeable part allows the corrosion of its longitudinal rebar. We replace exchangable part and attach new one when initiating crackings appear. The lasting part supports the axial load when the exchangeable part is replaced. We make four specimens, one is normal RC and other three specimens have the proposal structure. The controlled variables in the test are corrosion level and presence or absence of the bond between exchangeable part and lasting part. Replacement experiments and cyclic loading tests are conducted. Test results show that rebar replacement with axial force support is possible independent of corrosion level, and replacement with axial force support has no effect to the restoring force characteristics. The lack of the bond between exchangeable part and lasting part in replacement experiment changes crack characteristics. Shearing cracks open lager when the bond is lack, so it is preferable to ensure the strong bond considering the control of shearing cracks.